This invention relates generally to devices and methods for repair of heart valves, such as annuloplasty rings and bands, and more particularly to an annuloplasty band, annuloplasty band holder, annuloplasty sizer and annuloplasty method.
Annuloplasty prostheses, generally categorized as either annuloplasty rings or annuloplasty bands, are employed in conjunction with valvular reconstructive surgery to assist in the correction of heart valve defects such as stenosis and valvular insufficiency. There are two atrio-ventricular valves in the heart. That on the left side of the heart known as the mitral valve, and that on the right side known as the tricuspid valve. Anatomically speaking, each valve type forms or defines a valve annulus and valve leaflets. To this end, the mitral and tricuspid valves differ significantly in anatomy. Whereas the annulus of mitral valve is somewhat xe2x80x9cDxe2x80x9d shaped, the annulus of the tricuspid valve is more nearly circular.
Both valves can be subjected to or incur damage that requires that the valve(s) be repaired or replaced. The effects of valvular dysfunction vary. Mitral regurgitation has more severe physiological consequences to the patient than tricuspid valve regurgitation, a small amount of which is tolerated quite well. Many of the defects are associated with dilation of the valve annulus. This dilation not only prevents competence of the valve but also results in distortion of the normal shape of the valve orifice. Remodeling of the annulus is therefore central to most reconstructive procedures on the mitral valve. In this regard, clinical experience has shown that repair of the valve, when technically possible, produces better long-term results as compared to valve replacement.
Many procedures have been described to correct pathology of the valve leaflets and their associated chordae tendinae and papillary muscles. In mitral repairs, it is considered important to preserve the normal distance between the two fibrous trigones. The trigones almost straddle the anterior leaflet portion of the annulus. Between the left and right fibrous trigones the mitral annulus is absent (as described by Tsakiris A. G. xe2x80x9cThe physiology of the mitral valve annulusxe2x80x9d in The mitral valvexe2x80x94a pluridisciplinary approach. ed. Kalmanson D. Publishing Sciences Group, Acton, Ma 1976, pg 21-26). This portion of the mitral valve apparatus is formed by the change of the anterior portion of the base of the aorta into the (so called) sub-aortic curtain, and hence into the anterior leaflet of the mitral valve. A significant surgical diminution of the inter-trigonal distance could cause left ventricular outflow obstruction. Thus, it is highly desirable to maintain the natural inter-trigonal distance during and following mitral valve repair surgery.
Consequently, when a mitral valve is repaired (be it the posterior or anterior leaflet) the result is generally a reduction in the size of the posterior segment of the mitral valve annulus. As a part of the mitral valve repair, the involved segment of the annulus is diminished (i.e. constricted) so that the leaflets may coapt correctly on closing, or the annulus is stabilized to prevent post-operative dilatation from occurring. Either is frequently achieved by the implantation of a prosthetic ring or band in the supra annular position. The purpose of the ring or band is to restrict and/or support the annulus to correct and/or prevent valvular insufficiency. However, it is important not to over restrict the annulus or an unacceptable valvular stenosis could result. As described above, in mitral valve repair, constriction of the mitral annulus should take place only in the area of the posterior section of the valve annulus.
Shortening of the posterior portion of the mitral valve annulus may be accomplished in several ways. Firstly, by implanting a substantially inexpansible ring (smaller in size than the annulus). With this type of device the surgeon must accurately choose the size of ring that will just prevent insufficiency, yet will not cause significant valvular stenosis. Secondly, by using a contractible ring that may be complicated during implantation. This type has the disadvantage that the surgeon must then accurately judge not only the ring size to use, but also how to space the implanting sutures in the ring and the annulus so that, when implanted, insufficiency is minimized, yet there will be no significant valvular stenosis. Thirdly, and preferably, by a substantially inexpansible ring or band that may be contracted only in appropriate segments (and not in the anterior portion). The natural inter-trigonal distance should be maintained, and the anterior leaflet should not be diminished in circumference.
In tricuspid valve repair, constriction of the annulus usually takes place in the posterior leaflet segment and in a small portion of the adjacent anterior leaflet. The septal leaflet segment is not usually required to be shortened.
As described above, both annuloplasty rings and annuloplasty bands are available for repair of an atrio-ventricular valve. Examples of annuloplasty rings are shown in U.S. Pat. Nos. 5,306,296; 5,669,919; 5,716,397 and 6,159,240, the teachings of which are incorporated herein by reference. See, also, Duran C M G, et al. Clinical and Hemodynamic Perfornance of a Totally Flexible Prosthetic Ring for Atrioventricular Valve Reconstruction, (Annals of Thoracic Surgery 1976;22(5):458-63); and Duran C M G, Repair of Anterior Mitral Leaflet Chordal Rupture of Elongation (The Flip-Over Technique.) (Journal of Cardiac Surgery 1986;1(2):161-66.). A flexible annuloplasty ring has been available under the trade designation xe2x80x9cDURAN(trademark)xe2x80x9d by Medtronic, Inc., Fridley, Minn., USA. In general terms, annuloplasty rings completely encompass both the anterior and posterior portions of the valve annulus. The posterior portion is often diseased or dilated and not well supported by heart tissue. The anterior portion, in contrast, is well supported by surrounding heart tissue. Thus, it is possible that the annuloplasty ring may overtly support an otherwise healthy anterior portion, potentially leading to tissue failure.
Annuloplasty bands, on the other hand, are specifically designed to primarily encompass only a portion of the valve annulus. For example, a mitral valve annuloplasty band is typically configured to encompass only the posterior portion of the mitral valve annulus, thus promoting natural movement of the anterior portion. In addition to facilitating natural movement of the healthy portion of the valve annulus, annuloplasty bands can be implanted more quickly than annuloplasty rings, as fewer sutures are required. Examples of annuloplasty bands are shown in U.S. Pat. No. 5,824,066 and PCT International Patent Publication No. WO 00/74603, the teachings of which are incorporated hereby by reference. While viable, annuloplasty bands present other concerns. For example, if the band is only anchored into friable valve annulus tissue, there is some concern that the band may possibly pivot excessively relative to the valve annulus. Further, the profile (e.g., thickness) of prior annuloplasty bands may theoretically be sufficiently large so as to restrict or disturb blood flow. Thus, a need exists for an annuloplasty band adapted to provide reinforced attachment about the valve annulus, and a holder and a sizer that facilitate implantation thereof.
One aspect of the present invention relates to an annuloplasty band that is readily implanted to repair an atrio-ventricular heart valve, such as the mitral or tricuspid valve, and which may readily be secured (e.g., sutured) to the valve annulus tissue, for example to the antero-lateral and/or postero-medial trigones of a mitral valve. Another aspect of the present invention relates to methods of implantation of annuloplasty bands, for example, by suturing through eyelets adjacent the ends of the band to the valve annulus tissue. This provides an annuloplasty band that is anchored into the fibrous tissue of the valve (for example, in one embodiment, the antero-lateral and postero-medial trigones), which is believed to provide many of the advantages of annuloplasty rings, without sacrificing the advantages of an annuloplasty band. To this end, yet another aspect of the present invention relates to a holder for selectively maintaining the annuloplasty band during the implant procedure, the holder adapted to facilitate passage of sutures through the eyelets. Yet another aspect of the present invention relates to a sizer adapted to promote accurate evaluation of the valve annulus via sizer cut-out segments and sizer shape, and thus selection of an optimally sized annuloplasty band.
In one preferred embodiment, the annuloplasty band of the present invention comprises a sheath, and a generally arcuate stiffening element disposed within the sheath. The stiffening element extends from a first end to a second end, and includes eyelets at its first and second ends adapted to receive sutures to secure the annuloplasty band to a valve annulus.
In annuloplasty bands of the present invention intended for mitral valve repair, the stiffening element is preferably configured such that after implant, the stiffening element extends from a first end adjacent the antero-lateral trigone past the posterior leaflet to a second end adjacent the postero-medial trigone, and the eyelets are adapted to receive sutures to secure the annuloplasty band to the antero-lateral trigone and postero-medial trigone. Alternatively, in annuloplasty bands of the present invention adapted for tricuspid valve repair, the stiffening element is preferably configured to correspond with the natural tricuspid valve anatomy.
Preferably, the stiffening element comprises wire having opposite ends bent back onto itself to form the eyelets. The wire is preferably overmolded with an elastomeric material, such as biocompatible thermoplastic elastomeric or silicone material. The stiffening element is preferably radio-opaque.
Preferably, the sheath is fabric marked to indicate eyelet placement. For example, the fabric sheath may be marked to indicate eyelet placement by a suture of contrasting color to the fabric sheath.
In a second preferred embodiment of the present invention, the annuloplasty band generally comprises a sheath, and a generally arcuate stiffening element disposed within the sheath. The stiffening element has rounded ends, and the band has a thickness no greater than about 3 mm, preferably no greater than 2.7 mm, and most preferably no greater than 2.5 mm. The low profile annuloplasty band offers less restriction or disturbance to blood flow through the valve. Hence, the minimal cross-section annuloplasty band may reduce stenosis and turbulence, and may minimize the risk of thrombus formation.
In another preferred embodiment of the invention, a method of implantation of an annuloplasty band along the annulus of an atrio-ventricular valve to repair the valve generally comprises the following steps:
(a) Providing an annuloplasty band comprising a sheath and a generally arcuate stiffening element disposed within the sheath, the stiffening element extending from a first end to a second end, the stiffening element including eyelets at its first and second ends adapted to receive sutures to secure the annuloplasty band to a valve annulus;
(b) Positioning the annuloplasty band along the valve annulus to encompass a leaflet of the valve annulus, with the first and second ends of the stiffening element positioned adjacent desired portions of the valve annulus; and
(c) Suturing the eyelets to the valve annulus.
In one preferred embodiment, the above-described method relates to repair of a mitral valve. In this regard, the eyelets are preferably positioned adjacent the antero-lateral trigone and the postero-medial trigone, respectively. The eyelets are then preferably sutured to the valve annulus at the antero-lateral and postero-medial trigones. In an alternative embodiment, the above-described method relates to repair of a tricuspid valve. To this end, the annuloplasty band is positioned to surround the anterior, posterior and a portion of the septal leaflets of the tricuspid valve. The eyelets are sutured to the respective bases of the septal and anterior valve leaflets, adjacent the valve annulus and on either side of the antero-septal commissure to avoid impairment with the cardiac conduction system of the heart.
In still another preferred embodiment of the invention, a holder is provided in combination with an annuloplasty band. The annuloplasty band is mounted on the holder to help position the annuloplasty band relative to the valve annulus. The holder includes a band-retaining plate forming cut-out areas providing clearance about eyelets formed by the band, thereby promoting placement of sutures through the eyelets.
Yet another aspect of the present invention relates to a sizer for evaluating a size the valve annulus implant site and indicating which of a number of varying sized annuloplasty bands is best suited for the valve annulus. In a preferred embodiment, a plurality of differently sized sizers are provided, each corresponding in size with an annuloplasty band of the present invention. In this regard, each of the sizers preferably includes markings that identify a potential location of the corresponding annuloplasty band""s eyelets were the correspondingly sized band selected for implant. Along these same lines, the sizer delineates a distance between desirable points of the valve annulus. With respect to mitral valve repair procedure, the sizer affords a surgeon the ability to measure an intertrigonal distance and an area of a leaflet of the valve (e.g., anterior leaflet) in order to select an annuloplasty band that most closely matches those parameters.